A hearing aid or deaf aid is an electroacoustic device, which is designed to amplify sound for a user, usually with the aim of making speech more intelligible, and to correct impaired hearing as measured by audiometry. In the United States, hearing aids are considered medical devices and are regulated by the Food and Drug Administration (FDA). Therefore, ordinary small audio amplifiers or other plain sound reinforcing systems cannot be sold as “hearing aids”.
Earlier devices, known as ear trumpets or ear horns, were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal. Similar devices can include the bone anchored hearing aid, and cochlear implant. A primary issue that can minimize the effectiveness of hearing aids is called the compression effect. The compression effect takes place when the amplification needed to make quiet sounds audible, if applied to loud sounds, damages the inner ear (cochlea). Louder sounds are therefore reduced giving a smaller audible volume range and hence inherent distortion. However, hearing protection can also be provided by an overall cap to the sound pressure and impulse noise suppression, which is available in some high-end hearing aids.
The above-described background relating to hearing aids is merely intended to provide a contextual overview of hearing aid technology, and is not intended to be exhaustive. Other context regarding hearing aids may become further apparent upon review of the following detailed description.